1. Field of the Invention
The present invention relates to an active matrix type liquid crystal display intended for use as a display device in an OA device and the like for displaying images and character information. More specifically, the present invention relates to a semi-transparent liquid crystal display with a transparent region for allowing light to pass through a pixel region, and a reflective pixel electrode for reflecting ambient light.
2. Description of the Background Art
In a semi-transparent TFT (thin-film transistor) array substrate (which will also be referred to simply as “TFT array substrate”) adopted in a commonly-used conventional semi-transparent liquid crystal display, a transparent region for allowing backlight on the rear side of a display screen to pass therethrough, and a reflective region for reflecting ambient light entering a liquid crystal layer are formed in each pixel.
As a known structure and a manufacturing method of this TFT array substrate for use as a semi-transparent liquid crystal display, a reflective pixel electrode forming the reflective region, a source wiring with a source electrode and a drain electrode are formed in the same layer to simplify manufacturing process steps.
When the source wiring and the reflective pixel electrode are formed in the same layer in the semi-transparent liquid crystal display, certain space should be maintained between the source wiring and the reflective pixel electrode to avoid a damage caused by a short circuit therebetween. The lowermost layer of this space is provided with an auxiliary capacitive electrode and an auxiliary capacitive wiring. Thus an opposed electrode formed in a substrate opposite to the TFT array substrate is arranged to face the auxiliary capacitive electrode and the auxiliary capacitive wiring.
The technique relevant to the present invention is disclosed in Japanese Patent Application Laid-Open No. 2001-343660.
In the TFT array substrate with the conventional structure, the auxiliary capacitive electrode, auxiliary capacitive wiring and the opposed electrode are at the same potential. This means no electric field is applied to a liquid crystal layer between the auxiliary capacitive electrode, auxiliary capacitive wiring and the opposed electrode. As a result, light entering the display screen to be reflected by the auxiliary capacitive electrode and the auxiliary capacitive wiring provided between the source wiring and the reflective pixel electrode cannot be cut off by an electric field, leading to reduced reflective contrast.